1. Field of the Invention
The present invention relates to an air-conditioning apparatus for vehicle use that allows elimination of water adhering to an evaporator fin.
2. Related Art
In an air-conditioning apparatus for vehicle use known as a car air conditioner, an evaporator, heater core, and the like are disposed within an air duct, and air within the vehicle or air outside the vehicle is sent to the evaporator or heater core by means of a blower and is blown within the vehicle as conditioned air.
In order to perform highly efficient heat exchange with the air inside the vehicle (recirculate) or the air outside the vehicle, an evaporator is structured by installing a large number of fins on a tube through which refrigerant passes. In the cooling operation of the evaporator, the surface temperature of the fins is at or below the dew-point temperature of air, and so moisture in the air becomes frost or water droplets and adheres to the fins. When frost or water droplets adhere to the fins, the clearance between the fins is narrowed, the amount of air flow may be reduced, odors may be generated, and corrosion may be caused.
Odor generation and corrosion due to water droplets are susceptible to worsening in the case where the air conditioner is stopped for long periods such as when the vehicle is parked, and with regard to odor in particular the direct effect of blowing air containing unpleasant odors into the interior of the vehicle when restarting the air conditioner is unpleasant, to say the least, to passengers in the vehicle. For this reason, it is desirable to take measures so that water droplets do not continue to adhere to the evaporator when the vehicle is parked.
Japanese Patent Application Laid-open No. 54-159759 discloses a device directed to eliminating water droplets from an evaporator. This device forms a water-repellent film on the evaporator fin surface, facilitating the movement of water droplets and improving the water-shedding performance of the fins. Thus, water droplets that do form on the fins are easily blown away by blown air from the blower so that water droplets do not remain on the fins while the air conditioner is stopped.
When an air conditioner is switched off, the blower fan is rotated for a short time by inertia, but because the amount of blown air thereof decreases suddenly, water droplets adhering to the evaporator when the air conditioner is switched off cannot be blown away by means of air blown from the blower. Additionally, frost adhering to the evaporator melts and becomes water droplets after the air conditioner is switched off, and these water droplets also remain without being removed from the evaporator. Consequently, even if a water-repellent film is formed on the fin surface, the reliability of water removal thereof is not sufficient to remove all the water droplets that can form on the evaporator.